Medical equipment that uses ionizing radiation has found widespread application in the healthcare industry today. Allowing medical teams to diagnose and treat patients effectively, ionizing radiation has been used in different branches of medicine including, radiology, cardiology, neurology, oncology, trauma care, orthopedic surgery, endovascular intervention. The benefits of using x-ray imaging as a diagnostic tool and as a treatment option continue to grow. Non-communicable diseases (NCDs), which include cardiovascular diseases, cancer, diabetes and chronic respiratory diseases, have benefited greatly from the use of x-ray imaging. According to the World Health Organization, the global epidemic of NCDs is now the leading cause of death in the world.
The types of equipment that are typically used in these fields and responsible for the emission of ionizing radiation include CT scanners, fluoroscopes, and radiology x-ray cameras. Ionizing radiation is also prevalent in nuclear medicine and molecular imaging processes, where radioactive substances are introduced into a patient's body.
However, exposure to radiation typically results in serious side effects, including microscopic damage to living tissue. Tissue damage can sometimes cause skin burn or radiation sickness (also commonly referred to as “tissue effects”, or “deterministic effects”), and in some cases, cancer (“stochastic effects”). This type of tissue damage is a risk to both the patient, as well as the medical teams that work in these environments, because of secondary “scatter” radiation. Secondary scatter radiation is harmful radiation that the medical team is exposed to as a result of scattering off of a patient or other objects in the environment.
As a way of managing this tradeoff between potential benefit and potential harm from using x-ray, the concept of ALARA (As Low As Reasonably Achievable) has been introduced. ALARA is a radiation safety principle based on the assumption that every radiation dose of any magnitude can produce some level of detrimental effects, and ALARA is therefore aimed at minimizing radiation doses by employing all reasonable methods. In most parts of the world, ALARA is also a regulatory requirement.
The rate of medical radiation exposure has grown rapidly over the past several decades. Recent studies suggest that over half of the total radiation exposure to the general public comes from medical radiation. Studies further suggest that the exposure of the US population to ionizing radiation from diagnostic medical procedures had grown by more than seven times from the early 1980s. Procedures that contributed to this growth the most include CT-based procedures, nuclear medicine-based procedures, and interventional fluoroscopy.
Several recent trends show that fluoroscopic procedures will soon outpace CT-based procedures and become one of the types of procedures with the highest association to radiation exposure. For one, fluoroscopy guided procedures have become increasingly popular as they are commonly used to treat NCDs. Moreover, medical teams have been transitioning to minimally invasive x-ray guided surgery in favor of open surgery, especially with the rapid development of new endovascular techniques. Fluoroscopic procedures are expected to pose a higher risk of radiation exposure in comparison to CT-based procedures, in part due to recent advancements that have lowered the exposure in CT-based procedures. For example, improvements in CT scanning technology have made it possible to run CT scans using only a fraction of the radiation that was previously required. In contrast, radiation exposure metrics remain high for other x-ray guided procedures, such as interventional fluoroscopic procedures. Further, legislation and guidelines have recently been passed that limit the utilization of CT scans.
Compared to CT-based procedures, medical teams can change the operating settings of the x-ray equipment during the course of the fluoroscopic procedure. These operation settings are changed dynamically during the fluoroscopic procedure and affect the amount of radiation delivered to the patient and medical team, as well as the image quality produced by the equipment. Since the team is performing an operation on the patient during interventional fluoroscopy, it is not possible for them to reduce their own exposure by maintaining a large distance to the x-ray source while imaging, such as is the practice for diagnostic CT scans. There are a number of different input parameters that correspond to operating settings that may impact the level of radiation exposure delivered to the patient or the medical team, and these parameters may be interrelated or functionally dependent. For example, the radiation dose rate may be impacted by the path length that the central beam travels through the body, the patient's thickness, table and c-arm movement and angulation, the part of the body being imaged, the fluoroscopic pulse rate of the x-ray machine, fluoroscopic dose level (low/normal/high), cine acquisition (on/off), cine acquisition frame rate, C-arm detector height, collimation (square or round), the number of wedge filters being used, the magnification or Field of View (FOV), the use of Digital Subtraction Angiography (DSA), the changing of a patient's position (habitus) on the table, the dose protocols being used for specific procedures, x-ray tube voltages and currents, the use of beam shaping filters, the use of automatic dose rate control (ADRC), the location of the radiation source (above or below the patient table), or the use of an image intensifier instead of flat panel. A change to a single parameter or combination of parameters may change the radiation dose rate to the patient or medical team. However, it is very difficult for a medical professional to develop a good understanding of the harmful effects of such changes, since radiation is neither visible nor otherwise noticeable to humans. Further, changes to a single parameter or combination of parameters may change the quality of the x-ray image produced by the x-ray machine, something which may influence correct decision making in the delivery of treatment. Because these parameters may be interrelated or functionally dependent, accurately determining how a change to a parameter affects radiation dose rate or image quality is computationally complex. Yet, understanding the complex relationship between equipment settings, image quality and resulting exposure allows medical teams to minimize health risks to patients and themselves while optimizing image and treatment quality.
Currently, medical teams do not receive training that shows how a change to an operation setting during a fluoroscopic procedure causes a change to the radiation exposed to the patient or medical team. Despite the need for a detailed understanding of radiation reduction techniques, most medical teams today only receive a review of the basic concepts of radiation exposure, without any hands-on training. Training modules typically do not include any hands-on components, because there is currently no effective way of providing realistic hands-on training without using real radiation. Although some training programs use empty operating rooms and “phantoms” as substitutes for patients, several drawbacks exist. Specifically, these training programs still expose medical teams to secondary radiation and they block the operating room from being used for real procedures. Furthermore, they do not show how changes to operating settings during an operation cause changes in radiation exposure and image quality, or how operating settings may need to be changed at different points of an x-ray guided medical procedure to balance the trade-off between radiation exposure and image quality.
Although techniques and systems for measuring, estimating, and visualizing radiation exposure have been developed, none of the presently known art describes a comprehensive solution for training medical professionals or teams on the effects of operating setting adjustments and their impact on radiation exposure and image quality in a highly realistic and completely radiation-free simulated environment. The closer the simulation emulates the real world, the higher the transfer-of-training effect into the real operating room will be.
Further, systems for measuring, estimating, and visualizing radiation exposure do not show how changes in a simulation parameter affect radiation dynamically during the course of a procedure. Simulations that take into account multiple different simulation parameters are often computationally complex, and generally executed in a time- and resource-intensive Monte Carlo-style fashion. Further, to change a set of parameters, the simulation is generally re-executed, and thus, unable to effectively show how changes to a parameter affect radiation during a live procedure.
Moreover, systems for measuring, estimating, and visualizing radiation exposure do not provide any meaningful information about the risk levels associated with different levels of radiation exposure. In comparison to radiation exposure, there are generally no direct indications of the degree of risk. Integrating an effective means of showing how to assess health risk and evaluate damage is therefore needed.
Accordingly, there is a need for a training system that allows medical students, physicians and hospital staff to exercise the skills needed to minimize exposure during x-ray guided procedures in a hands-on, radiation-free and highly realistic environment. Further, there is a need for a training system that makes it easy for them to develop a thorough understanding of how the resulting dose will be affected by using different procedural techniques.